- You are here:
- Full Key
- All other flowering non-woody plants
- Daisies, goldenrods, and other aster family plants
- Eupatorium serotinum
Eupatorium serotinum — late thoroughwort
Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.
Facts
Widespread and common in the eastern half of the United States, late thoroughwort is nevertheless considered to be non-native in New England, where it occurs in Connecticut and Massachusetts.
Habitat
Anthropogenic (man-made or disturbed habitats), meadows and fields
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
Found this plant? Take a photo and post a sighting.
Characteristics
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Massachusetts
- Leaf type
- leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
- Leaf arrangement
-
- opposite: there are two leaves per node along the stem
- whorled: there are three or more leaves per node along the stem
- Leaf blade edges
-
- the edge of the leaf blade has no teeth or lobes
- the edge of the leaf blade has teeth
- Flower type in flower heads
- the flower head has disk flowers only, and lacks the strap-shaped flowers
- Ray flower color
- NA
- Tuft or plume on fruit
- at least a part of the plume is made up of fine bristles
- Spines on plant
- the plant has no spines
- Leaf blade length
- 50–200 mm
- Disk flower number
-
- 11-20
- 21-50
- 6-10
-
Flowers
- Bract color
- the bracts are not colored or tinged with pink, red or purple
- Bract cycle number
-
- there are three or more cycles of bracts
- there are two main cycles of bracts
- Bract keels
- the bracts do not have keels
- Bract outer side hair type
- the bracts are hairy, with simple hairs on their outer surface
- Bract outer side hairs
- the bracts are hairy on their outer surfaces
- Bract shape
-
- the main bracts are elliptic (widest near the middle and tapered towards the base and tip)
- the main bracts are oblong (roughly rectangular but rounded at the ends)
- Bract spines
- the bracts have no spines
- Bract tip orientation
- the bracts are pressed against the plant, or spreading out at the tips
- Bract tip shape
-
- the tips of the bracts acute (have a sharp point)
- the tips of the bracts are rounded
- Bract width
- 0.5–1
- Bracts
- there are at least two distinct forms of bracts in different cycles
- Disk flower color
- white
- Disk flower lobe number
- 5
- Disk flower number
-
- 11-20
- 21-50
- 6-10
- Disk flower reproductive parts
- the disk flower has both pollen- and seed-producing parts
- Disk flower shape
- the disk flower is tube-shaped (cylindrical), or gradually widening like a funnel
- Flower head number
- each flowering stem has four or more flower heads on it
- Flower head outer flowers
- at the outer edge of the flower head, the flowers have no enlarged lobe or strap, and are of similar size as those in the center of the disk
- Flower head platform
- the base has no bristles or papery scales
- Flower head platform surface
- NA
- Flower head position
- some or all the flower heads are grouped in clusters of two or more
- Flower head profile
-
- the disk is flat or nearly flat across the top
- the disk is rounded across the top
- Flower head shape
- the sides of the flower head diverge like a funnel
- Flower type in flower heads
- the flower head has disk flowers only, and lacks the strap-shaped flowers
- Height of flower head base
- 3–4 mm
- Inflorescence branching (Solidago)
- NA
- Inflorescence shape
- the inflorescence is flat-topped in profile
- Inflorescence stem
- hairs are present on the stem of the inflorescence
- Number of bracts at flower head base
- 8–12
- Ovary cross-section
- the ovary has five or more corners in cross-section
- Ovary hair type
- the ovary has no hairs on it
- Ovary hairs
- the ovary has no hairs on it
- Ovary lines or ribs
- there are four to six lines or ribs visible on the ovary
- Peduncle hairs
- the peduncles are hairy
- Ray flower color
- NA
- Ray flower reproductive parts
- NA
- Ray flowers
- NA
- Ray length
- 0 mm
- Reproductive system
- all the flowers on the plant contain both carpels and stamens
- Scale tip
- NA
- Smaller bracts at base of bracts
- there is a cycle of much smaller bracts outside the cycle of larger and longer bracts
- Style branch number
- the style has two branches
- Width of flower head base
- 1–6 mm
-
Fruits or seeds
- Number of pappus parts
- 11 or more
- Ovary length in developed fruit
- 1–1.5 mm
- Seed hair tuft details
- the pappus hairs are hooked or barbed
- Seed hair tuft length
- 2–2.5 mm
- Seed hair tuft tips
- at least some of the pappus hairs are broader at their tips than their bases
- Seed hairs uniform
- all the pappus hairs are approximately the same length
- Seed tuft scale number
- 0
- Seed tuft type
- the pappus is made of very fine hairs or bristles
- Top of disk flower ovary
- NA
- Tuft or plume on fruit
- at least a part of the plume is made up of fine bristles
-
Glands or sap
- Bract resin
- the bracts have resin or resin glands
- Leaf blade glands
- the leaf blades have glandular (translucent) dots or scales
- Ovary glands
- there are glands on the ovary surface
- Sap
- the sap is clear and watery
-
Growth form
- Growth form
- the plant has one or more free-standing stems
- Plant lifespan
- the plant is perennial, it shows evidence of previous year's leaves, stems or stem bases
- Spines on plant
- the plant has no spines
- Underground organs
- the plant has a caudex (the root mass is firm and hardened at the top)
-
Leaves
- Final leaf segment length (compound lvs only)
- 0 mm
- Final leaf segment width (compound lvs only)
- 0 mm
- Hairs on underside of leaf blade
- the underside of the leaf is fuzzy or hairy
- Hairs on upper side of leaf blade
- the upper side of the leaf is fuzzy or hairy
- Leaf arrangement
-
- opposite: there are two leaves per node along the stem
- whorled: there are three or more leaves per node along the stem
- Leaf blade base
- the leaf has a distinct petiole
- Leaf blade base shape
-
- NA
- the base of the leaf blade is rounded
- Leaf blade bloom
- the underside of the leaf has no noticeable bloom
- Leaf blade edges
-
- the edge of the leaf blade has no teeth or lobes
- the edge of the leaf blade has teeth
- Leaf blade hairs
- the leaf blade has simple hairs with no glands, and not tangled or wooly
- Leaf blade length
- 50–200 mm
- Leaf blade shape
-
- the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
- the leaf blade is ovate (widest below the middle and broadly tapering at both ends)
- Leaf blade surface colors
- there is no noticeable color variation on the upper surface of the leaf
- Leaf blade tip
-
- the tip of the leaf blade is acuminate (tapers to a long, thin point)
- the tip of the leaf blade is acute (sharply pointed)
- Leaf blade veins
- the leaf blade has one main vein running from the base towards the tip
- Leaf blade width
- 15–100 mm
- Leaf disposition
- the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
- Leaf spines
- there are no spines on the leaf edges
- Leaf stalk
- the leaves have leaf stalks
- Leaf stalk length
- 10–25 mm
- Leaf type
- leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
- Leaflet number
- 0
- Specific leaf type
- the leaves are simple (i.e., lobed or unlobed but not separated into leaflets
-
Place
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Massachusetts
- Specific habitat
-
- man-made or disturbed habitats
- meadows or fields
-
Stem, shoot, branch
- Flowering stem cross-section
- the flowering stem is circular, or with lots of small angles
- Leaves on stem
- there is at least one full leaf above the base of the flowering stem
- Stem bloom
- there is no powdery or waxy film on the stem
- Stem internode hair direction
- the hairs point mostly upwards to outwards
- Stem internode hairs
- the stem has hairs between the nodes
- Stem wings
- the stem does not have wings on it
Wetland status
Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)
In New England
Distribution
- Connecticut
- present
- Maine
- absent
- Massachusetts
- present
- New Hampshire
- absent
- Rhode Island
- absent
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- not applicable (S-rank: SNA)
From Flora Novae Angliae dichotomous key
9. Eupatorium serotinum Michx. E
late thoroughwort. CT, MA; also reported from RI by Magee and Ahles (1999), but specimens are unknown. Fields, roadsides, disturbed soil.
Native to North America?
Yes and no (some introduced)
Sometimes confused with
- Eupatorium altissimum:
- capitula with 5 disk flowers and leaves sessile or subsessile (vs. E. serotinum, with capitula with 9-15 disk flowers and principal leaves with petioles 10-25 mm long).